Grounding Issue/Electrical

I recently grounded a wall outlet that a Monster line conditioner said was ungrounded-- by extending the ground screw so it touched the wall of the outlet box. Now one line conditioner (a voltage stabilizer) shows that it is grounded, but the second line conditioner, which is plugged into the voltage stabilizer, does not show that the ground is okay or that the wiring is proper (lights are off or barely on). Anyone have any ideas or tips? Very much appreciated.
I would first make sure the outlet is good by using an AC outlet tester (about $5.00 from Radio Shack) instead of relying on the line conditioner lights. Then use the process of elimination, i.e., what happens when you plug in the second line conditioner into the wall instead of into the Monster, etc.
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The ground screw is just 'touching' the box? That doesn't sound like a good idea at all. That probably means an intermittent or high resistance connection at best.

Do yourself(and your gear) a favor: shut off the breaker, yank the outlet, run a self tapping screw through the back of the box and connect a chunk of 12ga bare copper between it and the ground screw on your outlet. Next, go to Rat Shack and get yourself an a/c circuit tester as suggested by Gs5556 above. Test accordingly.

If all is well, you're ready to reconnect your power conditioners and see that they are working properly(one of them could actually be part of the problem.) If not, it would be a good idea to consult an electrician to rectify the problem.